Coastal Shores and Marshes

Coastal Shores and Wetland Ecosystems in the Northern Appalachian / Acadian Ecoregion (final draft Anderson 3/31/06) Nova Scotia Beach/Dune Saltmarsh Prince Coastal fen Edward Island Tid al flat Coastal bog Figure 1. see text The coastline of the Northern Appalachian /Acadian ecoregion extends for 7,453 miles1 and is rich with almost 24,000 examples of beaches, salt marshes, tidal flats and distinctive rocky shores. Although coastal wetlands and shores cover less than 1% of the ecoregion (926,664 acres -Table 1) they are one of the most critical habitats in the region for biodiversity. Their importance to rare species, shore birds, and offshore fisheries is well known but population trends and conservation needs of the thousands of specialized organisms, (crabs, shellfish, amphipods and other macro/micro invertebrates) are not clearly understood. The distribution of coastal features within the ecoregion is correlated with shoreline orientation, exposure and complexity and tidal range. The complicated south- facing shorelines of Maine and Nova Scotia have extensive tidal flats and salt marshes tucked into nearly every cove and harbor (Figure 1). In contrast, the simpler shorelines that flank the Bay of Fundy have fewer examples of these features but terminate with massive tidal flats in the Cobequid Bay and Minas Basin region reflecting a tidal range that is the largest in the world. The east facing shores of New Brunswick and PEI have extensive barrier beaches and dunes while Quebec’s beaches and dunes are almost entirely located on the Magdalen Islands. (Table 1, Figure 2). 1 Including the coastline of Prince Edward Island and the Magdalen Islands 1 Table 1. The amount and size of coastal features within the ecoregion (features under 2 acres are excluded). Coastal Total Ave. AV AV AV AV AV Features Count Acres Size Min Max ME NB NS PE QC Coastal Shores Beach/Dune 2,745 47,992 17 0.1 1,095 24 10 19 48 Rocky Shore & Cliff 1,892 15,718 25 0.0 407 3 21 18 Coastal Wetlands Coastal Bog 706 51,513 73 0.1 5,077 ? 220 48 58 57 Salt pond 674 16,016 24 0.1 715 31 23 23 Salt/brackish marsh 6,818 138,384 20 0.0 4,427 6 38 16 15 143 Misc. fresh wetlands 3,409 34,534 101 0.0 749 6 40 67 5 2 Tidal flat 4,039 596,898 148 0.0 49,404 25 114 329 Aquatic bed 3,469 25,330 7 0.1 205 7 29 Grand Total 23,950 926,644 39 0.0 49,404 9 52 77 15 90 (Final numbers are in D/NAP/targets/models/90m/coastal/wetnap_cst705.xls It contains integrated USCANADA data as well as US and Canada separate columns) Figure 1. The distribution of coastal features by state and province. 3000 2500 s e c n 2000 e r r u c c O 1500 f o r e b m 1000 u N Salt/brackish marsh Tidal flat 500 Beach/Dune Rocky shore Salt pond 0 Coastal Fen ME NB Seasonal flooded flat NS PE QC 2 Biodiversity and Coastal features The coastal zone extends landward from the submerged aquatic beds just beyond the low tide line to the terrestrial margin where headlands, cliffs and dunes are found. The latter zone is marked by a definite change in material, physiographic form or a line of permanent vegetation, indicating the limit of the highest storm waves. Ecologists group the coastal shore and wetland features into a number of broadly defined ecosystem types based on structure, processes and composition as described below. Coastal Shores Headlands, Cliffs and Rocky shores: The rockbound coast of the ecoregion consists of bedrock shores punctuated by sandy interludes of beaches and dunes. Headlands with steep cliff faces jutting out into the sea are common. Subject to salt spray and wave pounding, headlands can be dramatic features while the related horizontal intertidal zone is the haven of algae, barnacles, snails and limpets. Coastal cliffs and isolated rocky islands are the preferred nesting habitat of black guillemot, black-legged kittiwake, razorbill and common murre. The lower shore zone subject to long periods of tidal inundation forms the habitat of rockweeds and brown seaweeds, mussels and Irish moss. Mapped examples of rocky shores and cliffs total to 904 miles of linear shoreline. Occurring in almost 2,000 distinct narrow segments averaging 25 acres in area, rocky shoreline is most abundant in areas of granite or mafic bedrock but may be found throughout the coastal region. Unconsolidated Beach and Dune Complexes: - Beaches are thick accumulations of unconsolidated water-borne, well-sorted sand and pebbles deposited on a shore, or in active transit along it. Dunes are transient mounds of loose, windblown sand, sometimes stabilized with vegetation. Beaches and dunes are ecologically linked but form distinct habitats, the former being periodically inundated and the latter dry and distinguished by vegetation adapted to constant sand burial. Typical plant species of beaches and dunes include: beach grass, sea rocket, sea-beach sandwort, seaside spurge, dusty miller, sea oats, seaside goldenrod, beach heather and bayberry. Although several of these species have wide ranges along the Atlantic coast they are otherwise narrowly restricted to this extremely specific and uncommon habitat. Beach nesting birds such as plovers and terns rely on exposed scrapes and isolation to prevent predation by mammals and other birds. Many are in decline due to loss of breeding habitat. Beaches cover almost 2249 miles of coast, although contiguous examples are small with two-thirds of the 2745 beach/dune occurrences being less than 10 acres in extent and 82% covering less than 20 acres. In several places, elongate barrier beaches have formed that parallel the shoreline but remain separated from it by a lagoon or marsh. Hog Island, a 1,100 acre barrier beach of Prince Edward Island boasts piping plovers, common terns, beach pinweed and broom crowberry, and is the largest example in the ecoregion. Coastal Wetlands and Marshes Tidal flat – Tidal flats are extensive, horizontal tracts of unconsolidated clays, silts, sands and organic materials that are alternately covered and uncovered by the tide. Most are sparsely vegetated but during low tide, shorebirds congregate in tidal flats, sometimes in vast numbers, to feast on their abundant burrowing invertebrates. Tidal flats make up 64% of the coastal wetlands mapped in the ecoregion. The largest example, 49,000 acres in the Minas Basin, is a huge and globally significant stopover site for migratory shore birds 3 Salt and Brackish marsh – Like tidal flats, salt marshes are flat, poorly drained areas subject to periodic inundation by salt water but salt marshes are covered with a thick mat of grassy salt- tolerant plants. These marshes may be further classified into saline marshes and brackish marshes depending on the salinity of the overwash water. Here they are treated as one system because our mapping units could not reliably separate the two. Brackish marshes typically occur in areas where there is a mixing between fresh and salt water such as at the mouth of a large river. Salt and brackish marshes are important to many of our rarest birds such as the salt marsh sparrow and willet. Specialized vegetation, exemplified by the dominant spartina grasses, have evolved mechanisms to resist desiccation and maintain salt balance in this extreme setting. Rare or declining plant species include seaside dock, saltmarsh sedge, seashore saltgrass, creeping alkali grass, American sea-blite, and small spikerush. There are over 6000 discrete salt and brackish marshes in the region ranging in size from 1 to 4000 acres. They occur in all parts of the coastline and amount to 140,000 acres in total. One of the largest (2,288 acres) occurs in the John Lusbie National Wildlife area in Cobequid Bay and is recognized as a globally significant bird area. Salt pond – Salt ponds are bodies of salt water in a marsh or swamp along the seacoast. They often have distinct shoreline vegetation such as seaside flatsedge and seaside crowfoot. Tidal marsh – Tidal marsh is a broad term used in this report to encompass both marshes and tidal flats. It refers to any extensive level marsh or flat regularly inundated by high tides. Coastal Bog – Cool maritime conditions favors the development of extensive bogs and fens in the coastal zone. Much like their inland counterparts these are areas of waterlogged, spongy ground, consisting primarily of mosses, containing acidic, decaying vegetation, such as sphagnum or sedges, which may develop into peat. Coastal bogs tend to be dominated by species such as broom crowberry and cottongrass that are minor components of inland systems. A number of rare orchids and carnivorous plants are found in this environment. Coastal Zone and Important Bird Areas. The unique importance of coastal shores, marshes, offshore waters or isolated islands to shorebirds has long been recognized. Many places in the ecoregion have been ranked globally and/or nationally significant for shorebird or seabird concentrations and threatened species. Some of the most important include: • Northeast Coastal Maine (ME) • Country Island Complex (NS) • Sable Island (NS) • Eastern Cape Sable Island (NS) • Cobequid Bay (NS • Malpeque Bay (PEI) • Southern Bight, Minas Basin (NS) • Brier Island (NS) • PEI National Park (PEI) • Iles-de-la-Madeleine (QU) 4 Coastal Shore and Wetland Portfolio Summary The screening criteria used to locate and identify coastal shore and wetland features most critical to maintaining biodiversity required that each qualifying occurrence: • Was contiguous and met size criteria: o Salt/Brackish marsh over 50 acres or part of a complex over 100 acres o Beach/dune over 20 acres o Coastal bogs over 75 acres o Tidal flats over 100 acres or part of a larger complex o Rocky shores and cliffs that were 2 acres minimum and part of a complex including some of the above features • Were in good landscape settings (Land Cover Index < 30) • Were in good condition based on ground surveys and expert opinion (corroboration by at least one source) • Contain other confirmed biodiversity features (element occurrences) Size criteria for the respective systems were determined by a literature analysis of minimum area requirements for the characteristic breeding species as well as information on the scale of specific disturbances (Tables 2 and 3, Figure 2).

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